Method of making an easy opening can end



April 22, 1969 E. c. FRAZE 3,439,641 I METHOD OF MAKING AN EASY OPENING CAN END Original Filed Jan. 29. 1965 Wren/rag,

Jnna/ .61 fra a United States Patent Oflice 3,439,641 Patented Apr. 22., 1969 3,439,641 METHOD OF MAKING AN EASY OPENING CAN END Ermal C. Fraze, 355 W. Stroop Road, Dayton, Ohio 45429 Original application Jan. 29, 1965, Ser. No. 429,063, now Patent No. 3,343,713, dated Sept. 26, 1967. Divided and this applicationApr. 14, 1967, Ser. No. 656,963

Int. Cl. B21d 51/44 U.S. Cl. 113-121 12 Claims ABSTRACT OF THE DISCLOSURE- This disclosure describes a method of making an easy opening container including an end panel in the container wall. The panel is secured to the container wall by roll forming together portions of both the panel and container wall. The panel thereafter has a tear strip formed therein and a tear tab attached thereto.

This application is a division of application Ser. No. 429,063, filed on J an. 29, 1965, and now Patent 3,343,- 713, issued Sept. 26, 1967.

This invention relates to a metal container having a portion of its wall weakened by scoring to form a tear strip that may be easily manually severed for access to the contents of the container. More particularly, the invention is directed to the problem of incorporating a panel or insert of relatively expensive, soft, non-ferrous metal in a container wall made of less expensive, tough, ferrous metal with a tear strip formed in the panel or insert.

The desirability of incorporating a panel of relatively soft meta for example, aluminum alloy, in a container wall of tough metal, for example, tin coated steel, arises from the fact that it is diflicult to form a readily separable tear strip in the tin coated steel. and too often the removal of the tear strip leaves a hazardous jagged edge. Undue manual force is required to remove a steeltear strip and if the tab is attached to the tear strip to serve as a handle for removing the tear strip, the excessive stressing of the metal structure required for severance of the metal is too apt to cause separation of the tab from the tear srip instead of separation of the tear strip from the container. Incorporation of a softer metal insert or panel into the steel container wall avoids these difficulties and combines the economy of making the container wall largely of steel with the advantage of fOl'Ining the tear strip in relatively soft metal, but the composite structure of the wall does present the problem of installing the panel or insert efficiently and economically in a fluidtight manner.

One heretofore suggested solution to this problem is to cut a substantially rectangular opening in the steel wall of the container and to place a flanged insert of softer sheet metal into the rectangular opening with the flange of the insert folded to grip the rim of the rectangular opening, a suitable sealant being employed to make the joint fluid tight. The panel insert is formed with a peripheral flange and nests into the rectangular opening in the manner of a plug with the insert folded into engagement with the rim of the rectangular opening around three sides of the insert. The insert is scored to form a tear strip which is continued as a free tongue that extends from the fourth side of the insert to serve as a tab or handle for removing the tear strip.

One disadvantage of this suggested solution is that the insert on the fourth side that forms the free tongue is not folded into positive gripping engagement with the rim of the rectangular opening because folding the tear strip on itself to form the joint would make it too difiicult, if not impossible, to pull the tear strip away from the insert. Consequently, the fourth side of the insert merely overlaps the rim of the rectangular opening instead of positively engaging the rim and only the interposed sealant is relied upon to make the joint fluid tight. In practice, it is only too easy for leakage to develop along this vulnerable part of the joint between the insert and the steel wall of the container and especially so because two slits are cut in the insert adjacent this part of the joint. Also, if the sealant is durable and thick enough to adequately seal the open section on the fourth side, the sealant because of its adhesive properties, renders diflicult the removal of the tear strip from the panel insert.

A further disadvantage is that removal of the tear strip exposes a strip of sealant adjacent the opening and the exposed sealant is not only unsightly, but also suggests the possibility of contamination when the contents of the container issue from the opening. The exposed sealant is especial-ly objectionable when the consumer drinks liquid directly from the container.

A further disadvantage of the suggested solution to the problem is that the surface of the aluminum insert is offset inwardly from the surface of the metal wall to form a recess or shallow well around the tear strip. The shallow well tends to trap dust and foreign material immediately adjacent the opening that is formed by the removal of the tear strip.

The present invention meets the above problem, in part, by forming an opening in the steel wall of the container that is of generally circular configuration instead of rectangular; in part, by positively mechanic-ally attaching the soft metal insert to the steel wall by means of a tightly rolled seam that is continuous around the rim of the opening; in part by locating the seam inside the container so that the outer surface of the insert may be flush with the outer surf-ace of the surrounding container wall, i.e., the exposed face of the insert is disposed in the same plane as the steel wall; in part, by spacing the whole tear strip in the insert radially inward from the surrounding continuous seam to avoid any conflict between the structural requirements of a tear strip and the structural requirements of a fluid tight seam; and, in part, by attaching a separate tab to the tear strip instead of forming one side of the insert with an integral tongue to serve as a tab.

To carry out this concept, the container wall is formed with an opening having a rim that curves without abrupt changes in direction, the opening being preferably of generally circular configuration, and the opening is formed with an inwardly turned flange. Usually, the container wall is a can top or end wall and, fortuitously, the flanged circular opening may be formed at no extra cost when the can end is stamped out of sheet steel stock. The soft metal insert is formed with a continuous marginal flange and initially the insert is nested into the opening of the container wall with the flange of the insert turned inwardly in face-to-face contact with the inward flange of the container opening. Since the two flanges are to be rolled together to form the continuous seam with the insert flange rolled over the container flange, the insert flange is preferably of greater axial dimension than the container flange and preferably the rims of both flanges are slightly flared or curved outward in advance of the seaming or curling operation.

A single die operation curls the two flanges into a continuous seam of substantially solid metal that makes it unnecessary to add sealant, although a plastisol sealant may be incorporated in the seam if desired. The plastisol sealant is particularly desirable to prevent anodic action where the can is intended to hold a substance which would 3 serve to produce an anodic action at the seam formed. The fact that the rim of the opening in the steel wall is curved without abrupt change in direction makes it possible to fabricate a seam that is uniform in cross section around the periphery of the insert. In the preferred practice of the invention, the rolled continuous seam protrudes into the interior of the container with the outer surface of the insert flush with the outer surface of the container wall. Preferably, but not necessarily, the rolled seam is subjected to a final compression operation to result in a relatively thin, flat seam with the layers of sheet material folded compactly for further assurance against leakage.

Other and additional advantages and features of the present invention will become apparent to those skilled in the art from a study of the accompanying specification and drawings which form a part thereof, and wherein:

FIGURE 1 is a plan view of a can end constructed in accordance with the teachings of this invention;

FIGURE 2 is a plan view of the underside of the can end illustrated in FIGURE 1;

FIGURE 3 is an enlarged cross-sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is an enlarged plan view of the top of the insert used in forming the can end illustrated in FIG- URES l-3 inclusive.

FIGURE 5 is a cross-sectional view of the insert of FIGURE 4 taken along line 55 of FIGURE 4 and looking in the direction of the arrows;

FIGURE 6 is an enlarged fragmentary cross-sectional view of that portion of the tin-coated steel material of the can end illustrated in FIGURES l3 inclusive, showing the opening into which the insert of FIGURES 4 and 5 is inserted;

FIGURE 7 illustrates schematically the positioning of the insert into the opening illustrated in FIGURE 6 and the dies for curling the flanges for permanently attaching the insert thereto;

FIGURE 8 shows the dies of FIGURE 7 in their closed position having curled flanges of the cam end and insert of the can end for an insured seal; and

FIGURE 9 illustrates schematically the dies for flattening the seamed jointure between the insert and body of the can end for an insured seal; and

FIGURE 10 is a fragmentary view, showing in section the flanges of the can end and insert as coated with the desired sealant prior to the curling or seam-forming operation.

FIGURES l, 2 and 3 show the completed can end 10 of the present invention having a curled peripheral edge 12 for connecting the end to the can body (not shown) and an insert or panel 14 mounted in an opening in the can end, the insert 14 being provided with a tear strip 16, formed by score lines 18, to one end of which a tab is permanently attached. Although the tab 20 can be permanently attached to the one end of the tear strip 16 by any suitable means, in the illustrated embodiment of the invention, the tab 20 is attached to the tear strip 16 by a hollow rivet 22 formed integral with the wall of the insert 14. The tab 20 forms a lever to be manually grasped by a user to bring about severance of the tear strip 16 from the insert 14. The tab 20, as illustrated more clearly in FIGURE 3, lies substantially flat and in close proximity with the top surface 24 of the can end to permit stacking of the can bodies in a conventional manner.

The body 26 of the can end 10 is formed from tinplated steel strip stock, commonly known in the industry as tin plate, while the insert 14 is formed of a suitable, relatively soft aluminum alloy. Since the tear strip 16 and the rivet 22 for attaching the tab 20 thereto are both formed out of the aluminum alloy of the insert 14, the opening of the sealed can is accomplished entirely within the area of the insert without the necessity of disturbing the surrounding tin plated steel. Thus the present invention provides a means of manually opening a can formed largely of tin plated steel by severing a tear strip formed solely of the aluminum alloy of the insert. This feature of the invention is advantageous in that the can end is easier to open and moderate manual force will not pull the tab away from the tear strip. At the same time, the can end formed in accordance with the teachings of this invention has the cost advantages of tin plated steel for a major portion of the can end.

Turning now to FIGURES 4 and 5, there is shown the aluminum insert 14 formed by any suitable method, such as by a stamping and forming operation. The insert as formed is provided with a downwardly extending integral peripheral flange 34 for purposes of attaching the insert permanently within the opening of the can end.

The main body portion 26 of the can end 10 is formed by any suitable method such as by stamping out of tinned steel sheet stock and is apertured as at 36 and provided with a downwardly extending peripheral hub or flange 38.

This hub or flange 38 is preferably provided with a flare 40 to cooperate with die means which, as will be later made clear, joins the insert to the cam end.

The joining of the insert into the flanged opening of the body portion 26 of the can end can be brought about by any means desired, and FIGURES 7 and 8 illustrate r schematically die means which may be used for permanently attaching the insert 14 to the body portion 26. As illustrated in these figures, the die means comprises an upper die or anvil 42 which is provided with a flat surface 44 which engages the top surface 24 of the can end and the top surface 30 of the insert after the latter has been placed in position in the aperture. A lower die 48 is formed with an annular groove or recess 50 which, as the dies are moved together, causes the flanges 34 and 38 to be rolled together to form a curled seam to permanently mount the insert in the opening 36 of the can end 10. The groove 50 has a diameter such that it contacts the lower end of the flange 34 of the insert, and as the dies 42 and 48 move forward one another, the surface of the groove forces the flanges 34 and 38 to curl within one another to form a seam, as illustrated at 56in FIGURE 8.

It is to be noted that flange 34 is slightly longer, i.e., extends downwardly further than flange 38 and the very end of the flange 34 i provided with a slight outwardly extending flare 58 similar to the flare 40 of the flange 38 to assist in the curling operation. The flare 58 may b formed on the flange 34 either before the insert is placed into the opening of the body portion or afterwards, as desired. Where the flare 58 is placed on the flange 34 before insertion of the insert 14 into the opening 36, then the insert must be inserted in the opening from the flanged side of the body portion, either before or after the body portion is placed in position on the anvil 42.

At this point, the installation of the insert 14 in the body portion 26 of the can end 10 may be regarded as finished since the curled or rolled seam 56 is of high mechanical strength and is liquid-tight even in the absence of sealant in the seam, although a plastisol sealant may be used. When a sealant is used, it is now preferred to coat the flanges 34 and 38 prior to the step of curling the flanges to form the seam 56. This coating step may be completed by merely dipping the flanges into a "bath of the sealant to form a film of the sealant on the flanges at least on the surface areas thereof shown "by FIGURE 10.

Moreover, if desired, the seam 56 may be flattened by an additional operation. For this purpose, the can end is then placed in another set of dies which includes an anvil-like die 60 and an upper die 62, and where the curled seam 56 is squeezed and flattened as shown at 64 as one die is moved toward the other.

After the can end 10 with the insert 14 is permanently joined thereto, lines of Weakness in the form of score lines are formed in the insert 14 to provide the serverable tear strip 16. The lines of weakness may be formed in any suitable configuration to form the severable tear strip such as,

for example, the tear strip illustrated in FIGURE 1 which when removed from the insert, provides a pouring spout through which the contents of the can may be discharged.

To permit the manual removal of the tear strip 16 to form the opening, the lever or tab 20 is permanently connected to the one end of the tear strip and although the tab 20 may be permanently joined to the tear strip by any joining method desired, in the illustrated embodiment of the invention the tab is joined to the tear strip by the rivet 22 formed integral with the planar wall of the insert 14. The integral rivet may be formed and the jointure completed by the method of my copending application, Serial No. 280,545, but however for-med, the rivet 22 extends through a flanged opening in the tab 20 after which the projecting end of the rivet is upset or staked to form an annular bead 70 clampingly mounting the tab 20 to the tear strip 16.

The tab 20 may be of any suitable construction, but in the illustrated embodiment of the invention comprises a segment of sheet metal having the edges thereof folded for strengthening purposes and divided into a minor end portion.72 that is connected to the hollow rivet 22 and a major portion 74 that constitutes a second class lever. Thus, the lever 74 is connected to the hollow rivet 22 by a web of sheet metal that is freely bendable along a dotted line 76 to permit the lever to swing relative to the rivet. The metal of the tab is formed with divergent slits 78 at the opposite ends of the dotted line 76 to provide the second class lever 74 with a pair of fulcrum ends 80 that extend beyond the dotted line and straddle the rivet 22 outside of the area of the tear strip 16. Thus, the lever has a forked fulcrum end and it is apparent that lifting the free end of the lever 74 swing the forked fulcrum end against the can end to apply a highly effective lifting force to the rivet 22 to initiate severance of the tear strip.

While the method has been described as first forming a tin end such as illustrated in FIGURES l, 2 and 3, it can be appreciated that the method of installing the insert could be performed prior to the time the tin end configurations have been severed from their original tinned steel sheet stock. Similarly, the work operations of scoring and attaching the tab to the insert may be performed on the insert prior to its being placed in the cutting and folding dies 42, 48 and 60, 62, the dies in this case being shaped to accommodate the tab and its means for joining the same to the insert so that the top surface 30 will lie coplanar with surface 26 of the can end.

It is to be stressed that while the invention is illustrated by showing a tab suitable to be attached to the tear strip 16 by a rivet integral with the insert 14, obviously the tab may be of any suitable type and attached to the tear strip in any conventional manner as by spot or pressure welding operations.

The present invention, as should now be understood, supplies a can end, the major or body portion 26 of which is formed of tin-plated steel but yet includes the insert 14 with its score lines providing a tear strip which can be easily removed as a tear strip of an all aluminum can end. Furthermore, the seamed attach-ment of the aluminum insert to the tin-plated steel body portion acts as an expansion joint which tends to resist internal pressures which ordinarily will cause a one-piece can end to bulge outwardly. As the seamed connection does serve an expansion joint, upon reduction of the pressure within the can, the can end will tend to return to its original unstressed position so that the seamed connection also serves a highly useful purpose where the can and its contents are subject to heat before the can is supplied to the market.

It should also be pointed out that even though the tinplated steel stock is apertured the exposed steel is not subject to direct engagement with the contents of the can with which the can end is used as the exposed steel edge is disposed internally of the seam after the seaming or curling operation has been completed. Thus there is n likelihood of the contents of the can reacting with the exposed steel of the body portion 26.

While only a single embodiment of the present invention is disclosed and described herein, it will be readily apparent to persons skilled in the art that numerous changes and modifications may be made without departing from the scope of the invention. Accordingly, the foregoing disclosure and description thereof are for illustrative purposes only and do not in any way limit the invention which is defined by the claims which follow.

I claim:

1. A method of fabricating a can end of coated steel sheet so that the end may be manually opened without the use of can openers and like tools, comprising:

forming an aperture in the coated steel sheet comprising the can end;

inserting a panel of softer sheet material in said aperture and joining the same to said coated steel sheet in leak-proof relationship by forming a continuous seam joining the panel to the defining edges of the aperture of the can end;

scoring the panel to form a tear strip severable from the panel; and

joining a tear tab to said tear strip so that the tear strip may be removed from the can end by manipulation of said tear tab. 2. A method of fabricating a can end of coated steel sheet so that the end may be manually opened without the use of can openers and like tools, comprising:

forming a flanged aperture in the coated steel sheet comprising the can end;

inserting a flanged panel of softer sheet material in said aperture and curling the flange of the panel onto the flange of said coated steel sheet in leak-proof relationship to form a continuous seam around the panel;

forming lines of scoring on the panel to provide a tear strip surrounded by the seam in spaced relation thereto; and

joining a tear tab to said tear strip so that the tear strip may be removed from the can end by manipulation of said tear tab to tear the softer sheet material along the score lines.

3. A method of fabricating a can end of coated steel sheet material so that the end may be manually opened without the use of can openers and like tools, comprising:

forming a flanged aperture in the coated steel material comprising the can end;

inserting a flanged panel of softer sheet material in said aperture and curling the flanges of said panel and can end to form a continuous uniform seam around the periphery of the panel;

flattening the continuous seam to fold the convolutions thereof;

scoring the panel to form a tear strip surrounded by the seam in spaced relation thereto; and

joining a tear tab to said tear strip so that the tear strip may be removed from the can and by manipulation of said tear tab to tear the softer sheet material along the score line.

4. A method of fabricating a can end of coated steel sheet so that the end may be manually opened without the use of can openers and the like, comprising:

forming a flanged aperture in the coated steel sheet comprising the can end;

inserting a panel of flanged softer sheet material in said aperture and placing said panel and coated steel sheet in die means for curling and folding the flanges together to form a continuous and uniform fluidtight seam permanently mounting the panel in the aperture of the can end;

scoring the panel to form .a tear strip surrounded by the seam in spaced relation thereto; and

joining a tear tab to said tear strip so that the tear strip may be removed from the can end by manipulation of said tear tab to tear the panel along the score line.

5. A method of fabricating a can end of coated sheet steel so that the can end may be manually opened without the use of can openers and like tools, comprising:

hermetically mounting a panel of softer sheet material in an aperture in the coated sheet steel comprising the can end by curling and folding edges of said panel and said aperture together to form a continuous jointure therebetween;

forming lines of weakness in the panel to form a tear strip severable from the panel; and

permanently securing a tear tab to said tear strip so that the tear strip may be removed from the can end by manipulation of said tear tab to sever the tear strip along the lines of weakness formed in said panel.

6. A method of fabricating a tough sheet metal container to make the container easy to open manually without the use of a can opener, characterized by the steps of:

forming an opening in the tough sheet metal wall of the container and further forming the opening with a continuous peripheral flange directed inwardly of the container;

forming a panel of softer sheet material with a continuous peripheral flange around the panel;

placing the panel in the opening with its flange directed inwardly and telescoped into the flange of the opening;

placing the telescoped assembly of container wall and panel between dies and closing the dies to curl the two flanges together to form a continuous fluid-tight seam around the periphery of the panel;

scoring the panel to form a tear strip in an area spaced radially inward from the continuous seam; and attaching a tab to the tear strip to facilitate severance thereof.

7. A method as set forth in claim 6 in which one of the dies has a planar surface to act against the outer surfaces of both the container wall and the panel to make the panel flush with the continer wall in the finished container.

8. A method as set forth in claim 6 in which the telescoped flanges are coated with a film of a sealant material prior to the formation of the seam.

9. A method as set forth in claim 6, which includes the step of pre-curling at least one of the two flanges.

10. A method of fabricating a tough sheet metal container to make the container easy to open manually without the use of a can opener, characterized by the steps of:

forming an opening in the tough metal wall of the container and further forming the opening with a continuous peripheral flange of a given axial dimension directed inwardly of the container; forming a panel of softer sheet material with a continuous peripheral flange of a larger axial dimension;

placing the panel in the opening substantially flush with the container wall and with its flange directed inwardly and telescoped into the flange of the opening;

placing the telescoped assembly of container wall and panel between dies and closing the dies to curl the two flanges together to form a continuous fluid-tight seam around the periphery of the panel;

scoring the panel to form a tear strip in an area spaced radially inward from the continuous seam; and attaching a tab to the tear strip to facilitate severance thereof.

11. A method as set forth in claim 10 which includes the step of slightly pre-curling the flange of the panel, before placing the panel in the opening.

12. A method as set forth in claim 11 which includes the step of slightly pre-curling the flange of the opening before placing the panel in the opening.

References Cited UNITED STATES PATENTS 3,163,317 12/1964 Biedenstein et al. 22054 3,361,291 1/1968 Fraze 1l3l21 RONALD D. GREFE, Primary Examiner. 

